Many uses of tobacco have been proposed. For example, tobacco has been smoked in pipes, and tobacco has been used for smoking in cigarettes and cigars. See, for example, Tobacco Production, Chemistry and Technology, Davis et al. (Eds.) p. 346 (1999). In recent years, there have been proposed various ways of providing many of the sensations of smoking, but without delivering considerable quantities of incomplete combustion and pyrolysis products that result from burning tobacco. See, for example, the background art set forth in U.S. Pat. No. 7,503,330 to Borschke et al. and U.S. Pat. No. 7,726,320 to Robinson et al., and U.S. patent application Ser. No. 13/840,264 to Novak, III et al., filed Mar. 15, 2013 and Ser. No. 13/647,670 to Gerardi, filed Oct. 9, 2012. Tobacco also has been enjoyed in so-called smokeless forms. See, for example, the background art set forth in US Pat. Pub. 2012/0272976 to Byrd et al. In addition, various materials derived from tobacco have been proposed to have uses in certain industrial applications. See, for example, U.S. Pat. No. 2,098,836 to Ressler; U.S. Pat. No. 2,232,662 to Hockenyos; U.S. Pat. No. 4,347,324 to Wildman et al. and U.S. Pat. No. 4,289,147 to Wildman et al., and US Pat. Pub. Nos. 2011/01287681 to DeVall and 2012/0260929 to Coleman et al.
Methods of extracting proteins from tobacco and tobacco components have been proposed in U.S. Pat. No. 9,301,544 to Mua et al., which is incorporated herein by reference. Certain methods for purifying such proteins and for compositions incorporating such proteins have been described in U.S. Pat. No. 9,175,052 to Gerardi et al. and US Pat. App. Publ. No. 2016/0029663 to Gerardi et al., respectively. It would be desirable to provide further methods for purifying tobacco-derived proteins, e.g., for inclusion in tobacco formulations useful in the manufacture of smoking articles and/or smokeless tobacco products, as well as for incorporation into other products such as nutritional supplements.